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Respiratory System. Introduction. Functions. Provide for gas exchange Intake of O2 Removal of CO2 Regulate blood pH Sense of smell Produces sounds Filters, warms, moistens air Water, heat balance. 3 Major Steps. Pulmonary Ventilation Moving air in and out of lungs - PowerPoint PPT Presentation
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Respiratory System
INTRODUCTION
Functions
• Provide for gas exchange• Intake of O2• Removal of CO2• Regulate blood pH• Sense of smell• Produces sounds• Filters, warms, moistens air• Water, heat balance
3 Major Steps
Pulmonary Ventilation• Moving air in and out of lungsExternal Respiration• Gas exchange between alveoli and bloodInternal Respiration• Gas exchange between blood and body cells
STRUCTURES AND FUNCTIONS
Upper Respiratory
Nose (nares)• Warm, humidify, filter dust• Olfactory stimuli• Modify vocal soundsPharynx• 3 regions• Tonsils, adenoids here• Eustachian tubes
Lower Respiratory
Larynx• “Voice box”• Thyroid cartilage• Epiglottis• Cricoid cartilage
Lower Respiratory
Trachea • Windpipe• Lined with ciliated mucous membrane; traps
dust and moves it upward• C-shaped rings of cartilage keep airway open
Lower Respiratory
Bronchi, Bronchioles • Bronchi contain cartilage rings• Primary (1° ) bronchi enter lungs• Secondary bronchi branch from 1°, one for
each lobe (3R, 2L)• Tertiary bronchi →→ terminal bronchi• Smaller airways have less cartilage, more
smooth muscle
Lower Respiratory
Lungs• Right lung has 3 lobes, left has 2• Surrounded by pleural membrane• Tertiary bronchioles divide into terminal
bronchioles• These lead to respiratory bronchioles, which
lead to the alveoli
Lower Respiratory
Alveoli• This is where gas exchange takes place• Surfactant cells secretes a substance that
keeps the alveoli from collapsing• Macrophages help fight infection
Pulmonary Ventilation
Volume and pressure are inversely relatedInhalation:• Contraction of diaphragm lowers the muscle
and lung volume ↑• Alveolar pressure ↓• Air enters lungs to equalize pressure
Pulmonary Ventilation
Exhalation:• Relaxation of the diaphragm raises the muscle
and lung volume ↓• Alveolar pressure ↑• Air rushes out
Air Flow
Frequency (f): Breaths/min; normal = 12Tidal Volume (TV): volume moved in one normal
breath• Normal = approx. 500ml• About 70% reaches alveoli• 30% remains in airwayMinute Ventilation (MV): f x TV = 6000 ml/min
Air Flow
Inspiratory Reserve Volume (IRV): volume of air that can be inhaled beyond TV
Expiratory Reserve Volume (ERV): volume of air that can be exhaled beyond TV
Residual Volume (RV): air remaining in lungs after ERV
Nature of Air
Mixture of gases – N2, O2, CO2, H2O, etc.Each gas exerts a partial pressureSum of partial pressures = atmospheric pressureEach gas diffuses down its pressure gradient• Example: O2 • In air, P = 105 mm Hg• In blood, P = 40 mm Hg
Breathing ControlBrain Centers:• Medullary rhythmicity area• 2 areas in the ponsFactors:• Voluntary adjustment (cortical)• Chemoreceptors• Limbic system; emotion, anticipation• Body temperature• Pain, airway irritation (cough, sneeze)